The wireless wars continue with AT&T's announcement Friday that it will give new and existing wireless subscribers a $100 bill credit to activate a new line of service for a smartphone on its device finance program.

In this latest move, AT&T is also pushing people away from its old contract model that requires consumers sign a two-year contract in exchange for a subsidized device. Instead, consumers are asked to pay full price for their devices either through finance programs, like AT&T Next, or outright at the time of purchase.

As part of the deal, AT&T's customers will not be required to put any money down to purchase a new phone. There's also no upgrade fee, no activation fee, and no annual contract. But they will be required to sign up for the AT&T Next device finance program, which offers customers the choice of two monthly installment plans. First, there is the AT&T Next 12, which allows customers to pay off their device over 20 months and upgrade at least once every 12 months. Or they can sign up for the AT&T Next 18 plan, which requires 18 monthly installments with the option to upgrade every 18 months.

The bill credit offer is only available until September 30, 2014. In order to qualify for the deal, the new phone must be bought through the AT&T Next installment plan. For customers wishing to upgrade after 12 months, they must have completed at least 12 months of payments, and the phone must be traded in to AT&T in order to get another new device.

Correction 7:22 a.m. PT:An earlier version of this story misstated the date the $100 bill credit promotion will end. The end date is September 30, 2014.